In U.S. Pat. No. 5,547,655, the inventors of the present invention disclose an electrochemical process for recovery and regeneration of sulfuric acid from the spent sulfuric acid catalyst of the alkylation of C3-C5 olefins and alkanes by using active intermediates generated by electrolysis, heat and photolysis. Both the organic impurities and water containing in the spent sulfuric acid catalyst are simultaneously removed under mild operating conditions. Over 90% water and 95% organic impurities of its initial value, respectively, are efficiently removed from the spent sulfuric acid catalyst, which avoids the disadvantages of the combustion of the corrosive spent sulfuric acid catalyst at high temperature, the purification and oxidation of SO2 at high temperature in the traditionally commercialized process.
In U.S. Pat. No. 5,547,655, preferably an oxidant such as an organic peroxide is introduced into the spent sulfuric acid catalyst to generate active intermediates from the surface of the anode during electrolysis. That is the active intermediates are generated substantively via anodic oxidation.